The mining is being conducted by the Oil Shale Mining Branch of the Office of Synthetic Fuels. The duties of this branch are: (1) To determine the extent of the oil shale resources in the United States, (2) to produce and deliver to the retorting plant selectively mined oil shale from any of 10 beds within the Mahogany Ledge that vary in richness and retorting characteristics and (3) to develop and demonstrate mining methods and equipment and determine the detailed costs for mining the Mahogany Ledge on a large scale. This paper will be confined to the third and most important phase of the mining.